It's not hard to transfer your record or tape collection to digital media. All you need is a PC or digital recorder with analog inputs and the patience to record your albums one at a time.

The tricky part is producing results that are free of the artifacts and noise that plague legacy recordings and poorly made digital copies. Most of us have learned to tolerate hiss, crackling, pops, and hum on analog media, but those defects can be hard to stomach in a pristine format like CD or DVD audio.

Audio restoration tools that address these problems range from simple freeware utilities to kilobuck programs designed for law enforcement and professional multimedia authors. Their features vary considerably, but most include all the tools you'll need to perform the tasks we describe here. In our examples, we use Tracer Technologies' application DC Live/Forensics ($1,399 direct), which offers some of the most advanced audio restoration and forensics tools available. Tracer also offers $59 and $199 versions of the program that perform many of the same functions (www.tracertek.com ).

Your restoration job will be much easier if you can control how you record your source material to digital. Avoid degrading quality with unnecessary format conversions by recording at the same sampling rate and bit depth as your final storage medium: 44.1 kHz, 16 bits for an audio CD; 48 kHz, 16 bits for a DVD video soundtrack encoded into Dolby Digital format; and 96/24 or 192/24 for DVD audio content.

Always record to an uncompressed format like WAV or raw PCM, and avoid ripping to lossy formats like MP3, which can play havoc with some noise reduction tools. Most important, watch your recording level. Unlike analog recording, digital sound produces nasty-sounding distortion if your level strays even slightly into the red, and even the best tools may not fix that. Choose a level that places your highest amplitude peaks at -3 dB or -6 dB.

Every recording has unique sonic characteristics that you'll need to analyze before deciding on a restoration strategy. Play your sound file over good headphones and listen for distortion, clipping, hiss, pops, and dropouts, then play it again on a speaker system that has enough low-end response to reveal subsonic noise. If your software includes a spectral analyzer, use it to generate a graph that shows fixed-frequency artifacts, like the 60-Hz hum produced by poorly grounded electronics. Once you've identified which flaws you want to correct, tackle them one at a time.

Start by filtering out any fixed-frequency noise. Most programs let you do this with a parametric equalizer, which provides definable tone controls that boost or cut any frequency range you choose. Parametric equalizers let you eliminate simple fixed-frequency noise components easily. But if you're trying to eliminate a more complex sound, like ground hum, you may also need to remove its first few (and most prominent) harmonics, which occur at 120 Hz, 180 Hz, and higher multiples of the 60-Hz fundamental frequency. Some programs provide hum and buzz filters that handle this automatically.

Your next target should be impulse noise, which includes short- duration artifacts like clicks, scratches, and crackling. Virtually all audio restoration programs provide declicking tools, with presets for different types of impulse noise, but you'll often need to make several passes, eliminating shorter-duration spikes each time. You may also wind up removing a few persistent clicks manually.

The trickiest part of most restoration jobs is eradicating continuous broadband noise, like tape hiss. The filters provided for this usually produce only modest results with default settings, and learning how to set each parameter takes a lot of experimentation. Don't try to operate a broadband-noise filter without reading the manual, and make sure your program has real-time preview capabilities.

Many broadband-noise tools try to determine optimal settings automatically by analyzing a short sample of your recording's noise. If your package offers this feature, select a sample that contains no sound other than the noise itself and is long enough to give the filter enough data (at least half a second). Even if the filter can't suggest perfect settings, a well-chosen noise sample should get you close.

If you've gotten this far, your sound file should be relatively noise-free. Don't be discouraged if it still isn't perfect. Cleaning up noise sometimes exposes difficult-to-remove types of distortion that weren't evident at the outset. Today's audio restoration tools excel at removing artifacts and noise, but they can rarely replace lost detail. Nonetheless, with the right tools and a little experimentation, you should be able to improve even the most severely compromised recordings.

Top Downloads

Automatic Renewal Program: Your subscription will continue without interruption for as long as you wish, unless
you instruct us otherwise. Your subscription will automatically renew at the end of the term unless you authorize
cancellation. Each year, you'll receive a notice and you authorize that your credit/debit card will be charged the
annual subscription rate(s). You may cancel at any time during your subscription and receive a full refund on all
unsent issues. If your credit/debit card or other billing method can not be charged, we will bill you directly instead. Contact Customer Service

//our current issue

Select Term:

24 issues for $29.99 ONLY $1.25 an issue! Lock in Your Savings!

12 issues for $19.99ONLY $1.67 an issue!

State

Country

This transaction is secure

Automatic Renewal Program: Your subscription will continue without interruption for as long as you wish, unless
you instruct us otherwise. Your subscription will automatically renew at the end of the term unless you authorize
cancellation. Each year, you'll receive a notice and you authorize that your credit/debit card will be charged the
annual subscription rate(s). You may cancel at any time during your subscription and receive a full refund on all
unsent issues. If your credit/debit card or other billing method can not be charged, we will bill you directly instead. Contact Customer Service